<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>200406</title>
</head>

<body>
    <script>
        // 输出12 算的7 太垃圾了呀你
        function side(arr) {
            arr[0] = arr[2]
        }
        function a(a, b, c = 3) {
            c = 10
            side(arguments)
            d = a + b + c
            console.log(d)
        }
        a(1, 1, 1)
    </script>
</body>

</html>